I agree with @derekprior that we probably want to test against the minor versions of Rails 3.x (i.e. 3.0.x, 3.1.x, 3.2.x), or just explicitly decide that we are supporting only the latest 3.x release. As this PR stands, Travis will only run against the latest 3.2.x.

If we want to support the minor versions of Rails 3, then we should specify each of the three versions in `Appraisal` file. Would be best if we can use the pessimistic operator for each minor versions. @jferris is that possible in `Appraisal`?